This contribution is made for oscommerce-2.2rc2a.
It Display's 2 prices; Incl VAT (tax) and Excl VAT (tax) in products_new.php, product_listing.php, advanced_search_result.php and Product_Info.php
The location of excl. price in the column of product_listing_php, can managed in admin -> configuration -> product listing
You can use different languages, just add the language files.....
Screenshots are also inside the package
* Note: Make sure you have Display Prices with Tax set to True in Configuration -> My Store, Admin section.